The character not related to chondrichthyes is

Options

A. Claspers
B. Placoid scales
C. Filamentous gills
D. Heterocercal caudal fin

Answer

To determine which character is not related to Chondrichthyes, we need to analyze the characteristics of this class of fishes. Chondrichthyes, commonly known as cartilaginous fishes, include sharks, rays, and skates. Here’s a step-by-step breakdown:

### Step 1: Understand Chondrichthyes Characteristics
Chondrichthyes are characterized by:
- A skeleton made of cartilage instead of bone.
- Presence of paired fins.
- Jawed structure.
- Gills that are typically lamelliform (plate-like) rather than filamentous.
- Scales that are tooth-like, known as dermal denticles or plesoid scales.
- Claspers in males for reproduction.
- Heterocercal caudal fin (the upper lobe is larger than the lower lobe).

### Step 2: Analyze the Options
Now, let's analyze the options provided:
1. **Claspers** - Present in male Chondrichthyes.
2. **Plesoids** - Refers to the type of scales found in Chondrichthyes.
3. **Scales** - Chondrichthyes have scales (dermal denticles).
4. **Filamentous** - This term refers to a type of gill structure that is not found in Chondrichthyes.
5. **Gills** - Chondrichthyes have gills, but they are lamelliform.
6. **Heterocerical caudal fin** - This is a characteristic feature of many Chondrichthyes.

### Step 3: Identify the Incorrect Character
From the analysis, the only option that does not relate to Chondrichthyes is **Filamentous gills**. Chondrichthyes possess lamelliform gills, not filamentous gills.

### Conclusion
The character not related to Chondrichthyes is **Filamentous gills**.

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